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Merge branch 'bpf, sockmap: Fix infinite recursion in sock_map_close'

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Jakub Sitnicki says:

====================

This patch set addresses the syzbot report in [1].

Patch #1 has been suggested by Eric [2]. I extended it to cover the rest of
sock_map proto callbacks. Otherwise we would still overflow the stack.

Patch #2 contains the actual fix and bug analysis.
Patches #3 & #4 add coverage to selftests to trigger the bug.

[1] https://lore.kernel.org/all/00000000000073b14905ef2e7401@google.com/
[2] https://lore.kernel.org/all/CANn89iK2UN1FmdUcH12fv_xiZkv2G+Nskvmq7fG6aA_6VKRf6g@mail.gmail.com/
---
v1 -> v2:
v1: https://lore.kernel.org/r/20230113-sockmap-fix-v1-0-d3cad092ee10@cloudflare.com
[v1 didn't hit bpf@ ML by mistake]

 * pull in Eric's patch to protect against recursion loop bugs (Eric)
 * add a macro helper to check if pointer is inside a memory range (Eric)
====================

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Alexei Starovoitov 2023-01-24 21:32:55 -08:00
commit e8c8fd9b83
4 changed files with 111 additions and 47 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
include/linux/util_macros.h
View File

@ -38,4 +38,16 @@
*/
#define find_closest_descending(x, a, as) __find_closest(x, a, as, >=)
/**
* is_insidevar - check if the @ptr points inside the @var memory range.
* @ptr: the pointer to a memory address.
* @var: the variable which address and size identify the memory range.
*
* Evaluates to true if the address in @ptr lies within the memory
* range allocated to @var.
*/
#define is_insidevar(ptr, var) \
((uintptr_t)(ptr) >= (uintptr_t)(var) && \
(uintptr_t)(ptr) < (uintptr_t)(var) + sizeof(var))
#endif

33
net/core/sock_map.c
View File

@ -1569,14 +1569,15 @@ void sock_map_unhash(struct sock *sk)
psock = sk_psock(sk);
if (unlikely(!psock)) {
rcu_read_unlock();
if (sk->sk_prot->unhash)
sk->sk_prot->unhash(sk);
return;
}
saved_unhash = READ_ONCE(sk->sk_prot)->unhash;
} else {
saved_unhash = psock->saved_unhash;
sock_map_remove_links(sk, psock);
rcu_read_unlock();
}
if (WARN_ON_ONCE(saved_unhash == sock_map_unhash))
return;
if (saved_unhash)
saved_unhash(sk);
}
EXPORT_SYMBOL_GPL(sock_map_unhash);
@ -1590,16 +1591,17 @@ void sock_map_destroy(struct sock *sk)
psock = sk_psock_get(sk);
if (unlikely(!psock)) {
rcu_read_unlock();
if (sk->sk_prot->destroy)
sk->sk_prot->destroy(sk);
return;
}
saved_destroy = READ_ONCE(sk->sk_prot)->destroy;
} else {
saved_destroy = psock->saved_destroy;
sock_map_remove_links(sk, psock);
rcu_read_unlock();
sk_psock_stop(psock);
sk_psock_put(sk, psock);
}
if (WARN_ON_ONCE(saved_destroy == sock_map_destroy))
return;
if (saved_destroy)
saved_destroy(sk);
}
EXPORT_SYMBOL_GPL(sock_map_destroy);
@ -1615,9 +1617,8 @@ void sock_map_close(struct sock *sk, long timeout)
if (unlikely(!psock)) {
rcu_read_unlock();
release_sock(sk);
return sk->sk_prot->close(sk, timeout);
}
saved_close = READ_ONCE(sk->sk_prot)->close;
} else {
saved_close = psock->saved_close;
sock_map_remove_links(sk, psock);
rcu_read_unlock();
@ -1625,6 +1626,12 @@ void sock_map_close(struct sock *sk, long timeout)
release_sock(sk);
cancel_work_sync(&psock->work);
sk_psock_put(sk, psock);
}
/* Make sure we do not recurse. This is a bug.
* Leak the socket instead of crashing on a stack overflow.
*/
if (WARN_ON_ONCE(saved_close == sock_map_close))
return;
saved_close(sk, timeout);
}
EXPORT_SYMBOL_GPL(sock_map_close);

4
net/ipv4/tcp_bpf.c
View File

@ -6,6 +6,7 @@
#include <linux/bpf.h>
#include <linux/init.h>
#include <linux/wait.h>
#include <linux/util_macros.h>
#include <net/inet_common.h>
#include <net/tls.h>
@ -639,10 +640,9 @@ EXPORT_SYMBOL_GPL(tcp_bpf_update_proto);
*/
void tcp_bpf_clone(const struct sock *sk, struct sock *newsk)
{
int family = sk->sk_family == AF_INET6 ? TCP_BPF_IPV6 : TCP_BPF_IPV4;
struct proto *prot = newsk->sk_prot;
if (prot == &tcp_bpf_prots[family][TCP_BPF_BASE])
if (is_insidevar(prot, tcp_bpf_prots))
newsk->sk_prot = sk->sk_prot_creator;
}
#endif /* CONFIG_BPF_SYSCALL */

81
tools/testing/selftests/bpf/prog_tests/sockmap_listen.c
View File

@ -30,6 +30,8 @@
#define MAX_STRERR_LEN 256
#define MAX_TEST_NAME 80
#define __always_unused __attribute__((__unused__))
#define _FAIL(errnum, fmt...) \
({ \
error_at_line(0, (errnum), __func__, __LINE__, fmt); \
@ -321,7 +323,8 @@ static int socket_loopback(int family, int sotype)
return socket_loopback_reuseport(family, sotype, -1);
}
static void test_insert_invalid(int family, int sotype, int mapfd)
static void test_insert_invalid(struct test_sockmap_listen *skel __always_unused,
int family, int sotype, int mapfd)
{
u32 key = 0;
u64 value;
@ -338,7 +341,8 @@ static void test_insert_invalid(int family, int sotype, int mapfd)
FAIL_ERRNO("map_update: expected EBADF");
}
static void test_insert_opened(int family, int sotype, int mapfd)
static void test_insert_opened(struct test_sockmap_listen *skel __always_unused,
int family, int sotype, int mapfd)
{
u32 key = 0;
u64 value;
@ -359,7 +363,8 @@ static void test_insert_opened(int family, int sotype, int mapfd)
xclose(s);
}
static void test_insert_bound(int family, int sotype, int mapfd)
static void test_insert_bound(struct test_sockmap_listen *skel __always_unused,
int family, int sotype, int mapfd)
{
struct sockaddr_storage addr;
socklen_t len;
@ -386,7 +391,8 @@ close:
xclose(s);
}
static void test_insert(int family, int sotype, int mapfd)
static void test_insert(struct test_sockmap_listen *skel __always_unused,
int family, int sotype, int mapfd)
{
u64 value;
u32 key;
@ -402,7 +408,8 @@ static void test_insert(int family, int sotype, int mapfd)
xclose(s);
}
static void test_delete_after_insert(int family, int sotype, int mapfd)
static void test_delete_after_insert(struct test_sockmap_listen *skel __always_unused,
int family, int sotype, int mapfd)
{
u64 value;
u32 key;
@ -419,7 +426,8 @@ static void test_delete_after_insert(int family, int sotype, int mapfd)
xclose(s);
}
static void test_delete_after_close(int family, int sotype, int mapfd)
static void test_delete_after_close(struct test_sockmap_listen *skel __always_unused,
int family, int sotype, int mapfd)
{
int err, s;
u64 value;
@ -442,7 +450,8 @@ static void test_delete_after_close(int family, int sotype, int mapfd)
FAIL_ERRNO("map_delete: expected EINVAL/EINVAL");
}
static void test_lookup_after_insert(int family, int sotype, int mapfd)
static void test_lookup_after_insert(struct test_sockmap_listen *skel __always_unused,
int family, int sotype, int mapfd)
{
u64 cookie, value;
socklen_t len;
@ -470,7 +479,8 @@ static void test_lookup_after_insert(int family, int sotype, int mapfd)
xclose(s);
}
static void test_lookup_after_delete(int family, int sotype, int mapfd)
static void test_lookup_after_delete(struct test_sockmap_listen *skel __always_unused,
int family, int sotype, int mapfd)
{
int err, s;
u64 value;
@ -493,7 +503,8 @@ static void test_lookup_after_delete(int family, int sotype, int mapfd)
xclose(s);
}
static void test_lookup_32_bit_value(int family, int sotype, int mapfd)
static void test_lookup_32_bit_value(struct test_sockmap_listen *skel __always_unused,
int family, int sotype, int mapfd)
{
u32 key, value32;
int err, s;
@ -523,7 +534,8 @@ close:
xclose(s);
}
static void test_update_existing(int family, int sotype, int mapfd)
static void test_update_existing(struct test_sockmap_listen *skel __always_unused,
int family, int sotype, int mapfd)
{
int s1, s2;
u64 value;
@ -551,7 +563,7 @@ close_s1:
/* Exercise the code path where we destroy child sockets that never
* got accept()'ed, aka orphans, when parent socket gets closed.
*/
static void test_destroy_orphan_child(int family, int sotype, int mapfd)
static void do_destroy_orphan_child(int family, int sotype, int mapfd)
{
struct sockaddr_storage addr;
socklen_t len;
@ -582,10 +594,38 @@ close_srv:
xclose(s);
}
static void test_destroy_orphan_child(struct test_sockmap_listen *skel,
int family, int sotype, int mapfd)
{
int msg_verdict = bpf_program__fd(skel->progs.prog_msg_verdict);
int skb_verdict = bpf_program__fd(skel->progs.prog_skb_verdict);
const struct test {
int progfd;
enum bpf_attach_type atype;
} tests[] = {
{ -1, -1 },
{ msg_verdict, BPF_SK_MSG_VERDICT },
{ skb_verdict, BPF_SK_SKB_VERDICT },
};
const struct test *t;
for (t = tests; t < tests + ARRAY_SIZE(tests); t++) {
if (t->progfd != -1 &&
xbpf_prog_attach(t->progfd, mapfd, t->atype, 0) != 0)
return;
do_destroy_orphan_child(family, sotype, mapfd);
if (t->progfd != -1)
xbpf_prog_detach2(t->progfd, mapfd, t->atype);
}
}
/* Perform a passive open after removing listening socket from SOCKMAP
* to ensure that callbacks get restored properly.
*/
static void test_clone_after_delete(int family, int sotype, int mapfd)
static void test_clone_after_delete(struct test_sockmap_listen *skel __always_unused,
int family, int sotype, int mapfd)
{
struct sockaddr_storage addr;
socklen_t len;
@ -621,7 +661,8 @@ close_srv:
* SOCKMAP, but got accept()'ed only after the parent has been removed
* from SOCKMAP, gets cloned without parent psock state or callbacks.
*/
static void test_accept_after_delete(int family, int sotype, int mapfd)
static void test_accept_after_delete(struct test_sockmap_listen *skel __always_unused,
int family, int sotype, int mapfd)
{
struct sockaddr_storage addr;
const u32 zero = 0;
@ -675,7 +716,8 @@ close_srv:
/* Check that child socket that got created and accepted while parent
* was in a SOCKMAP is cloned without parent psock state or callbacks.
*/
static void test_accept_before_delete(int family, int sotype, int mapfd)
static void test_accept_before_delete(struct test_sockmap_listen *skel __always_unused,
int family, int sotype, int mapfd)
{
struct sockaddr_storage addr;
const u32 zero = 0, one = 1;
@ -784,7 +826,8 @@ done:
return NULL;
}
static void test_syn_recv_insert_delete(int family, int sotype, int mapfd)
static void test_syn_recv_insert_delete(struct test_sockmap_listen *skel __always_unused,
int family, int sotype, int mapfd)
{
struct connect_accept_ctx ctx = { 0 };
struct sockaddr_storage addr;
@ -847,7 +890,8 @@ static void *listen_thread(void *arg)
return NULL;
}
static void test_race_insert_listen(int family, int socktype, int mapfd)
static void test_race_insert_listen(struct test_sockmap_listen *skel __always_unused,
int family, int socktype, int mapfd)
{
struct connect_accept_ctx ctx = { 0 };
const u32 zero = 0;
@ -1473,7 +1517,8 @@ static void test_ops(struct test_sockmap_listen *skel, struct bpf_map *map,
int family, int sotype)
{
const struct op_test {
void (*fn)(int family, int sotype, int mapfd);
void (*fn)(struct test_sockmap_listen *skel,
int family, int sotype, int mapfd);
const char *name;
int sotype;
} tests[] = {
@ -1520,7 +1565,7 @@ static void test_ops(struct test_sockmap_listen *skel, struct bpf_map *map,
if (!test__start_subtest(s))
continue;
t->fn(family, sotype, map_fd);
t->fn(skel, family, sotype, map_fd);
test_ops_cleanup(map);
}
}